It is known to produce deposits of solids, especially metals or metal compounds, on high-surface area solid substrates, forming coatings a few molecules or atoms thick; and to form liquid dispersions of finely divided particles of such solids; which preparations are capable of catalyzing chemical reactions taking place upon the surface of such coatings or particles; such catalysis is known as heterogeneous catalysis and the catalysts are called heterogeneous catalysts. In the prior art, heterogeneous catalysts consisting of a deposit on a solid substrate have been produced, usually, by impregnating a substrate having high surface area per gram (called in this context a catalyst carrier or catalyst support) with a solution of a catalyst precursor compound which can be converted, for instance by heating or by chemical reaction, into an active catalytic form; drying the resulting impregnated carrier; repeating the impregnation with precursor and drying as necessary to deposit a sufficient quantity of the catalyst precursor on the carrier; and converting the precursor to an active supported catalyst.
Suspensions of active catalyst have been provided by forming a solution or dispersion of catalyst precursor in a suitable liquid and converting the precursor to catalytically active form by chemical reaction such as for example reduction.
It is also known to produce a stream of metal atoms, ions or clusters with high kinetic energies by use of a laser beam to blast such particles out of a metal surface. If such metal takes the form of a coating upon a transparent substrate, and the back of the metal coating is exposed through the transparent substrate to laser radiation, then a stream of mostly neutral metal atoms is vaporized from the front of the coating. See Review of Scientific Instruments, Vol. 45, No. 1, January 1974 pp. 50 and 52-56.